This invention relates to an electrophotographic copying machine incorporating a mechanism which computes and selects desired magnification or copy paper size according to detected or input document (text paper) size.
Recently, a wide variety of electrophotographic copying machines with variable magnification, used to perform photocopying by enlarging or reducing document images, have been commercialized. When photocopying with these electrophotographic copying machines, document size, desired magnification and copy paper size must be determined. For this reason, some copying machines incorporate document size detectors in the plate (document table). A plurality of optical sensors are placed under the plate in positions corresponding to the right end of a documents of specific size so that copy paper size matching the maximum sensor position--out of multiple sensors--is defined as the document size. This copying machine incorporates a mechanism which computes and selects a document size upon entry of data on desired magnification or a desired magnification based on entry of data on document size as identified by the said detector and on operator-input magnifications or copy paper size. However, when an unformatted document sized between B5 and A4 is placed on the plate, its right end comes to a point between the B5R and A4 sensors. In this instance, the A4 sensor, but not B5R sensor, detects the document inserted. The document size detector therefore detects the document as if it is of A4 size and photocopies in variable magnifications based on operator-specified magnification or copy paper size. However, since the unformatted document is longer than A4 paper in the exposure scanning direction, copying would allow an enlarged image to overflow the copy paper used, generating waste.
Thus conventional copying machines with variable magnifications equipped with document size detectors generate waste copies when reproducing unformatted or irregular sized documents, thereby substantially lowering operating efficiency.